Spearfishing Dangers – Blackouts

Shallow water blackout has been recognised as a major hazard for spearfishers for years. The facts of the matter confirm that blackouts are the most dangerous hazard that spearfishers have to face. Blackouts from diving are caused by one thing: lack of oxygen. There are three

Loss of Motor Control

It is the least severe form of blacking out. This is also called a “Samba”. It can be as mild as a flickering of the eyes or slight trembling of the body or at the other end of the scale it can be a complete loss of control with the body violently shaking. A samba happens when the diver arrives at the surface,or during his first breath or up to 8 – 10 seconds later. (It takes that
time from the first breath for the oxygen to reach the brain.) It is a partial blackout and in most cases
the diver will be able to recover unassisted. However in a severe samba, the diver might not be able to hold their head above the water and would drown if unassisted.

Shallow Water Blackout

It is called this because it occurs close to the surface. The biggest change of pressure happens in the top 10 metres of water. When ascending, this pressure change can have the effect of reducing the oxygen level in the blood and when someone has dived past their safe limit it causes a blackout. Unassisted, it is very unlikely a diver will survive a shallow water blackout.

Deep Water Blackout

Occurs when a diver has exceeded his limit by a long way making it possible for him to blackout even before he reaches the 10 metre danger zone. This does not happen often. Blackouts and Sambas all occur because a person exceeded their safe limits. These events become fatal if the diver doesn’t have a competent diving partner who knows what to do in an emergency.